Rebound hardness measuring device



Oct. 6, 1953 M. D. BRAID 2,654,244

REBOUND HARDNESS MEASURING DEVICE Filed Dec. 6, 1949 2 Sheets-Sheet l Oct. 6, 1953 v M. D. BRAID 2,654,244

REBOUND HARDNESS MEASURING DEVICE Filed D90. 6, 1949 2 Sheets-Sheet 2 7 2 Q fl F2 2 T [NVEJYLUP Murray Dozggzcxsfiz gzd Patented Oct. 6, 1953 REBOUND HARDNESS MEASURING DEVICE Murray Douglas Braid, Painesville, Ohio, assignor to Thompson Products, Inc., Cleveland, Ohio,

a corporation of Ohio Application December 6, 1949, Serial No. 131,317

5 Claims. 1

This invention relates to improvements in measuring devices and more particularly relates to an improved measuring device adapted to measure the hardness of materials by measuring the rebound of a hammer dropped from a predetermined elevation. Y

Heretofore, the hardness of metals and other materials has commonly been measured by an instrument known to the trade as Shores Standard Scleroscope. In this instrumenta diamond tipped drop hammer is hung at the top of a glass tubein readiness to test the hardness of the material. The dropping of the hammer is controlled by a bulb which, when pressed, exerts pressure on a cylinder and moves a cam to open a valve to the tube chamber to admit air therein. The cam then releases the hammer. In order to bring the hammer back to its initial position the bulb again must be pressed to move the cam to a neutral position to permit the valve to close and position the hanger to engage the drop hammer as it moves upwardly along the tube. When the valve is closed and the bulb is suddenly released, a vacuum is created in the tube chamber by release of the bulb to draw up the drop hammer to such an elevation that it may be caught and held by the hooks of the measuring device.

Such measuring devices have been designed primarily as laboratory instruments and for this reason have never been satisfactory for production' use, the reasons being that they must frequently be readjusted and the operation of the bulbis slow and tiresome and creates a serious fatigue factor making it impractical and unduly expensive to use these-instruments to measure the hardness of articles on a production basis.

' A principal object of my invention is to remedy these difficulties by providing a rebound hardness testing instrument so arranged as to increase the life of the device and decrease fatigue factors present in operating the instrument by constructing it for positive operation by suction supplied and controlled externally of the instrument.

A further object of my invention is to provide a new and improved form of rebound testing instrument, the operation of which may be controlled by'the simple shifting of a mechanical valve remote from the instrument.

A still further object of my invention is to pro vide a novel and improved form of rebound hardness testing instrument for metals so constructed as to be operated in a more facile and positive manner than formerly and to reduce the frequency the device must be regulated to maintain its accuracy.

A still further object of my invention is to provide a rebound testing instrument of a simpler poses in which all operations of the device may be lease of the piece to be tested and all operations controlled by suction supplied from an external source, together with fluid operated means for holding the piece to be tested in position and a single control means controlling holding and reof the hardness testing device.

These and other objects of my invention will appear from time to time as the following specification proceeds and with reference to the accom-' panying drawings wherein:

Figure l is a fragmentary front end view of a hardness testing instrument constructed in accordance with my invention and with the front cover thereof removed in order to show certain details of construction thereof;

Figure 2 is a fragmentary transverse sectional view taken substantially along line II.II of Figure 1; and

Figure 3 is a diagrammatic view illustrating the piping and electrical connections for operating the hardness testing device and holding or releasing the piece of work being tested.

The hardness testing instrument of my invention, as shown in Figures 1 and 2 of the drawings,- is constructed along lines similar to the Shore Standard Scleroscope, the detailed construction and principle of operation of which are well known to those skilled in the art, so the parts similar to those of the 'Scleroscope need only herein be shown and described in sufficient detail to make my present invention readily understandable.

The hardness testing device includes generally a tube l0 which may be made of glass or any other suitable transparent material protected at its rear end portion and sides by a shield l l. The tube l 0' is open and graduated at its front so that the rebound of a diamondtipped drop hammer l2,-slidab1y mounted therein, may readily be observed and noted. The tube Hi may be protected at its bottom by a metal end piece l3 open at its center to permit the end of the hammer l2 to drop therethrough onto the piece of metal being tested (Figure 3). The end piece [3 may be connected to a casing I 4 encircling the upper end of the shield H by spaced rods |5-|6 extending along opposite sides of the tube l and secured to a yoke l8 extending across the lower end of said casing, as by machine screws The testing device may be suitably supported on a bench (not shown) and may be vertically adjusted with respect to the work being tested in any suitable manner well known to those skilled in the art so not herein shown or described.

The hammer |2 is slidably mounted in the tube In to freely drop therealong when released and fits closely enough within said tube that it may be moved upwardly to it initial operating p0sition by suction. The hammer I2 is held in position to be dropped on the piece of work to be tested by a hanger consisting of a pair of hooks l9 pivoted intermediate their ends on a horizontal pivot pin 23. Pivotal pin 20 is mounted in the side Walls of a tube chamber 2| enclosed by the casing I4 and spaced upwardly from and in alignment with the open upper end of the tube Id. The hooks |3-| 9 are urged in position to engage the shoulders of a recessed top portion of the hammer l2 to hold said hammer in position to drop by means of a spring 22 engaging opposite upper ends of the hooks. The hooks |9|9 are released by an internal cone 23 encircling the upper end portions of said hooks and engageable with projecting portions 25-25 thereof and pivoting the hooks |9|9 inwardly toward the center of the tube l0 upon downward movement of said cone 23 into engagement with said projecting portions. The cone 23 is herein shown as being of an internal frusto-conical formation engaging the under portion of a valve element 26. A compression spring 21, seated in a shouldered portion 29 of the tube chamber 2|, engages the cone 23 and urges said cone into engagement with said valve element 26 and into position to allow the hooks |9I9 to engage the hammer I2. The spring 21 also urges the valve element 26 in position to close the upper end of tube chamber 2| and prevent the entrance of air therein at atmospheric pressure from the head of the instrument.

The valve element 25 has a resilient upper face 30, formed from rubber Neoprene or any other suitable material and mounted on the top face of said valve element and adapted to be seated against a downwardly facing shouldered portion 3| of the tube chamber 2| to prevent the passage of air from the head I5 into said tube chamber.

The valve element 26 is moved into position to open, and the cone 23 is moved downwardly against the spring 2'! to release the hanger hooks |9-|9 from the drop hammer l2 by means of a cam 33 operated by suction in a vacuum chamber or cylinder 34. A piston 35 is mounted in cylinder 34 for movement therealong and is urged into extended position by a compression spring 3'! interposed between the head end of the cylinder 34 and said piston. A passageway 3Q entersthe head end ofthe cylinder 34 from one side thereof through a connecting lug 4|! extending therefrom. A vacuum or suction line 4|, which may be a rubber hose, is herein shown as being connected thereto to create a vacuum in the cylinder 34 and move the piston 35 toward the head end thereof against the compression spring 31.

The piston 35 has a central web 43 having a coupling member 44 secured thereto and extending from the side thereof opposite the spring 31. The coupling member 44 is herein shown as being of a bifurcated formation and has a link 46 pivotally connected thereto between the furcations thereof by a pivotal pin 41. The opposite end of the link 46 from the coupling member 44 is pivotally connected to a depending arm 49 of a rocking member 50. The rocking member 53 is pivotally mounted on a transverse shaft 5| mounted adjacent its ends in support bosses 53-53 extending inwardly from opposite side walls of the head l5. The rockin member is pivotally mounted on a reduced portion 54 of a spacing collar 55 pivotally mounted on the transverse shaft 5| and abuts one face of said spacing collar. A pin 56 is provided to lock said rocking member to said collar. The cam 33 is mounted on a reduced portion 5'! of the spacing collar 55 and abuts the opposite end thereof from the rocking member 50 and is secured thereto as by a pin 58. The creation of suction within the suction chamber 34 will thus move the piston 35 against the spring 31 toward the head end thereof and will pivotally move the cam 33 in a counterclockwise direction engaging a high portion 59 thereof with a roller 60 to depress said roller.

The roller 60 is mounted between the furcations of an upright plunger 6| on a pivotal pin 62. The plunger 6| is herein. shown as bein an upward extension of the valve element 25 and as being slidably guided in the upper end wall of the tube chamber 2 l.

A stop 63 projects upwardly from the rocking member 5|] and is adapted to engage a shouldered portion 54 of an adjusting screw 65 threaded in a rear end wall of the head l5 and serves to limit rocking movement of said rocking member in a release direction.

Thus upon the creation of a vacuum in the vacuum chamber 34, the cam 33 will move in a counter-clockwise direction, the high portion 59 thereof depressing the plunger 6| to open the valve to the tube chamber 2| and admit air to said chamber at atmospheric pressure and also moving the internal cone 23 into engagement with the projecting portions 2525 of the hooks Ill-I8 to release the hammer l2 and allow it to drop along the tube l0 onto the work to be tested. When it is desired to raise the drop hammer along the tube It), air at atmospheric pressure is admitted to the suction line 4| and passageway 39. This allows the spring 31 to move the piston 35 away from the head end of the suction cylinder 34. This will move cam33 in a clockwise direction through the link 46 and rocking member 50 and will allow the roller 60 to ride into the low portion of said cam. The spring 2! will then disengage the cone 23 from the hooks |9-|9 and close the valve formed by the gasket 30 engaging the shouldered portion 3| of the tube chamber 2 I. At this time, suction is created in the tube chamber 2| through a fitting 66 threaded therein and opening to said chamber and having a suction or vacuum line 61 secured to'its outer end and connected'to a source of vacuum. This will suck the hammer l2 upwardly along the tube l0 into engagement with the hooks |9--|9 to hang said drop hammer'in said tube until released by the cone 23.

Referring now to Figure 3, a vacuum pump 68 is diagrammatically shown as being connected with a four-Way valve 69 by a suction line 10. A vacuum release valve H is herein shown as being providedin said. suction line. The vacuum pump 58 may be of any well-known form, driven from a suitable electric motor, and is not herein shown or described in detail since it is no part of my present invention.

and move the cam 33 in a direction to release the drop hammer l2. In this position of the valve 69, the suction line El is opened to pressure from the atmosphere. When the valve 69 is in an opposite position, the suction line 61. is connected with the vacuum pump 58, thus creating a vacuum in the tube chamber 21 to return the drop hammer l2 into engagement with the hanger hooks l9-l 9, it being understood that during this position of the valve 65 the release of vacuum from the vacuum chamber 34 will allow the spring 31 to move the cam 33 in a position to permit the spring 27 to close the tube chamber from pressure from the atmosphere and to move the cone 23 out of engagement with the projecting portions 25-25 of the hanger hooks I9l 9.-

' The hardness measuring instrument is shown in Figure 3 as being supported in position to test the hardness of the valves of the type used in internal combustion engines. Each valve 13 is diagrammatically shown as being held in position to be tested by a fluid operated vise Hi operated by a double'acting cylinder 15. The cylinder is diagrammatically shown as having a piston 16 movable therein with a piston rod H extending therefrom and operatively connected with the vise M to clamp the jaws of the vise around the stem of the valve. The testing device may be suitably supported on the top of a table or work bench (not shown) and the vise 98 may be mounted on one side thereof'facing the operator of the'instrument,'and after the hardness of the work piece has been tested the jaws of the vise'may be released to allow the piece to drop into a basket or' carrier.

Fluid under pressure may be provided to operate the vise by means'of a suitable fluid pump (not shown) which may be of any form well known to those skilled in the art.' A pressure line l8 may lead from said pump to a solenoid operated four- Way valve 79. A return line 83 may lead from said valve to discharge air to the atmosphere. A pressure line 8! is shown as leading from one port of the four-way valve :Qto the head end of cylinder F5. Another pressure line 83 leads from another port of the four-way valve it to the piston rod end of the cylinder 75. The four-way valve is is shown as being operated by a solenoid 84 having an armature 85 extending therethrough. As herein shown, the armature 85 is operatively connected with the valves l9 and 69 and also forms the armature of the solenoid 12. The solenoid 12 thus moves the armature 85 in one direction and moves the two valves in one position of operation to connect the suction line A! with the vacuum pump 63 and at the same time connect the pressure line 3! with the pressure line is and cause the vice M to grip the article being tested, it being understood that the timing of the gripping operation of the piece to be tested and dropping of the hammer i2 is such that the vice i l first grips the piece to be tested and holds it in position, and the hammer i2 is then released. to drop on the piece.

The solenoids "l2 and 8 3 are herein shown as being operated by a switch 86. The switch 86 Thus, when may be of'a'n ywellknown form operated either by the hand or foot, but for thesake of convenience may preferably be a foot operated switch This switch is shown as being of a double throw type having a contact arm 87 engageable with a contact 83 to close a circuit to the solenoid 84 through a conductor 88. The other contact of the switch 86 is connected through contact arm 81 with the solenoid "through a conductor 90. The other terminals of the solenoids 84 and 59 are connected to a source of power supply by means of conductors 9| and 92.

When foot pressure is exerted on the switch 86 a circuit is completed through the solenoid 84,

energizing said solenoid and clamping the test hardness reading noted, the foot may be released.

from the switch 86. The contact arm 81 will then close a circuit through the conductor 90 to energize the solenoid l2 and reverse operation. of the vacuum valve 69 and the fluid pressure control valve 19; The valve 19 will then supply fluid under pressure to the piston rod end of the cylinder .15 and release the vice 14, allowing the piece tested to drop therefrom. Reversal of the four-way vacuum valve 69 will open .the vacuum line til to pressure from the atmosphere, permitting the spring 3! to return the piston 35 to the piston rod end of the cylinder 34 and move the cam 33 into a position to allow the spring 21 to close the tube chamber 2|. Itwill also create a vacuum in the tube chamber 2| to suck the hammer 2! to the topof the "tube 19 for engagement by the hooks 19-49 to be held thereby in-position for the next testing operation.

It will be understood that modifications and variations may be effectedv without departing from the scope of the novel concepts of the present invention. I

s I claim as my invention:

1. In a hardness testing instrument including a tube chamber, a tube leading therefrom, a hammer guided within said tube to drop therealong onto the material to be tested, means within said chamber operable to hold said hammer in an elevated position in said tube, a suction outlet for said chamber for applying suction therein and. raising said hammer along said tube in no: sition to be engaged by said holding means, a valve closing said tube chamber and movable into position to admit air therein, means movable with said valve for releasing said holding means upon opening of said valve, a rotatable cam operable to move said valve to an open position, spring means moving said valve to a closed position, the improvements comprising a suction cylinder, a piston therein, a connection between said piston and cam moving said cam into position to open said valve and release said hammer upon the creation of suction within said cylinder, spring means engaging said piston and moving said cam into position to allow closing of said valve, a vacuum pump, a second valve, a suction line connecting said pump with said second valve, separate suction lines connecting said second valve with said cylinder and said tube chamber, said second valve also having communication with the atmosphere, and means for operating said second valve to selectively connect said pump to establish a vacuum in either said suction cylinder or said tube chamber.

2. In a control means for a hardness testing device including a reboundable hammer, means for holding said hammer in an elevated position ready to be dropped on the material to be tested, suction means for returning the hammer to its elevated position, other suction means for releasing the hammer, a valve controlling the creation of suction in both of said suction means, a vise disposed beneath said hardness testing device to hold the piece to be tested, fluid operated means for moving said vise to a gripping and released position, a valve controlling operation of said fluid operated means, and a single control member controlling operation of both of said valves to cause said vise to grip the piece to be tested and to then release said hammer to drop on the piece to be tested and to then release said vise and create suction to return the hammer to its elevated position.

3. In a control means for a hardness testing device including a reboundable hammer, means for holding said hammer in an elevated position ready to be dropped on the material to be tested, suction means for returning the hammer to its elevated position, other suction means for releasing the hammer, a vacuum pump, a valve connecting said vacuum pump to both of said suction means, a vise disposed beneath said hardness testing device to hold the piece to be tested, fluid operated means for moving said vise into gripping and released positions, a valve controlling the operation of said fluid operated means, electrical means for operating said valves, and a single switch operable to energize said electrical means and move said valves to certain operative positions to cause said vise to grip the piece to be tested and to then connect said vac uum pump to said suction means for releasing said hammer to drop on the piece to be tested when said switch is in one position and to release the said vise and connect said vacuum pump to said suction means to return said hammer to its elevated position.

4. In a control means for a hardness testing device including a reboundable hammer, means for holding said hammer in an elevated position ready to be dropped on the material to be tested, suction means for returning the hammer to its elevated position, other suction means for releasing the hammer, a vacuum pump, a valve connecting said vacuum pump to both of said suction means, a vise disposed beneath said hardness testing device to hold the piece to be tested, fluid operated means for moving said vise into gripping and released positions, a valve controlling the operation of said fluid operated means,

electrical means for operating said valves including two solenoids having a common core connecting said valves together, and a single switch operable to alternately energize said solenoids to effect movement of said valves into position to effect gripping of the piece to be tested by said vise and to connect said vacuum pump to said suction means to release said hammer and create suction therein and release said hammer to drop on the piece to be tested and to release said vise and connect said vacuum pump to said suction means to return said hammer to an elevated position to create suction therein and return said hammer to be dropped on the next piece to be tested.

5. An instrument for measuring the hardness of metals comprising a chamber, a tube extending therefrom, a hammer slidable within said tube, a valve controlling the entrance of air to said chamber at atmospheric pressure, means for holding said hammer in an elevated position in said tube, a rotatable cam engageable with said valve to open said valve to place said chamber in communication with air at atmospheric pressure and to release said holding means, a suction cylinder having a piston therein, a link connecting said piston with said cam, spring means moving said piston along said cylinder in a direction to move said cam into position to accommodate said valve to close, a-source of suction, a suction line connected to said cylinder to create suction therein and effect movement of said piston against said spring means and movement of said cam in a direction to open said valve and release said holding means to'drop said hammer, a second suction line connected to said chamber to establish suction therein and to effect raising of said hammer along said tube into position to be dropped, and a single valve connecting said source of suction to said suction lines and also connecting said suction lines to the atmosphere and operable when in one position to create suction in said cylinder and connect the suction line leading to said chamber to atmosphere and when in a second position to create suction in said chamber and connect said suction line leading to said cylinder to atmosphere.

MURRAY DOUGLAS BRAID.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,121,050 Shore Dec. 15, 1914 2,424,177 Lawshe et al July 15, 1947 2,427,151 Mick Sept. 9, 1947 

